FontCache is an extension that is used
by X-TrueType to cache informations about fonts.

FontCacheQueryExtension
returns True if the FontCache extension is available on the given display.
A client must call FontCacheQueryExtension before calling any other Xfontcache
function in order to negotiate a compatible protocol version; otherwise
the client will get undefined behavior (Xfontcache may or may not work).

FontCacheQueryVersion returns True if the request succeeded; the values
of the major and minor protocol versions supported by the server are returned
in major_versionp and minor_versionp .

FontCacheGetCacheSettings should
be documented here. Returns True on success or False on failure.

FontCacheChangeCacheSettings
should be documented here. Returns True on success or False on failure.

FontCacheGetCacheStatistics should be documented here. Returns True on
success or False on failure.